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Date:   Fri, 24 Jun 2022 11:38:06 -0700
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Subject: Re: [PATCH v5 07/22] x86/virt/tdx: Implement SEAMCALL function
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To:     Kai Huang <kai.huang@intel.com>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Cc:     seanjc@google.com, pbonzini@redhat.com, len.brown@intel.com,
        tony.luck@intel.com, rafael.j.wysocki@intel.com,
        reinette.chatre@intel.com, dan.j.williams@intel.com,
        peterz@infradead.org, ak@linux.intel.com,
        kirill.shutemov@linux.intel.com,
        sathyanarayanan.kuppuswamy@linux.intel.com,
        isaku.yamahata@intel.com
References: <cover.1655894131.git.kai.huang@intel.com>
 <095e6bbc57b4470e1e9a9104059a5238c9775f00.1655894131.git.kai.huang@intel.com>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <095e6bbc57b4470e1e9a9104059a5238c9775f00.1655894131.git.kai.huang@intel.com>
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On 6/22/22 04:16, Kai Huang wrote:
> SEAMCALL instruction causes #GP when SEAMRR isn't enabled, and #UD when
> CPU is not in VMX operation.  The TDX_MODULE_CALL macro doesn't handle
> SEAMCALL exceptions.  Leave to the caller to guarantee those conditions
> before calling __seamcall().

I was trying to make the argument earlier that you don't need *ANY*
detection for TDX, other than the ability to make a SEAMCALL.
Basically, patch 01/22 could go away.

You are right that:

	The TDX_MODULE_CALL macro doesn't handle SEAMCALL exceptions.

But, it's also not hard to make it *able* to handle exceptions.

So what does patch 01/22 buy us?  One EXTABLE entry?